4,4″-dihydroxy-p-terphenyls are useful not only as intermediate raw materials for production of various kinds of resins such as liquid crystalline polyesters, polycarbonates, polyurethanes, polyimides or polyamides but also as raw materials for various kinds of liquid crystal materials exemplified by liquid crystal display elements, raw materials for photoresists for use in the production of semiconductors, or as raw materials for organic electroluminescence elements.
1,4-bis(4-hydroxyphenyl)-1-cyclohexenes are themselves useful as intermediate raw materials for production of various kinds of resins similarly to 4,4″-dihydroxy-p-terphenyls as mentioned above. They are also useful as intermediate raw materials for the production of a variety of organic compounds or liquid crystal materials. For example, the dehydrogenation of the cyclohexene portion of the molecule of 1,4-bis(4-hydroxyphenyl)-1-cyclohexenes provides 4,4″-dihydroxy-p-terphenyls as above mentioned.
In turn, 4-(4′-(4″-hydroxyphenyl)cyclohexyl)-1-hydroxy-benzenes are themselves useful as intermediate raw materials for production of various kinds of resins or liquid crystal materials similarly to 4,4″-dihydroxy-p-terphenyls as mentioned above. In addition, they provide 4,4″-dihydroxy-p-terphenyls as above mentioned when they are dehydrogenated.
Hitherto known dihydroxyterphenyls such as 4,4″-dihydroxy-p-terphenyl which has a symmetrical molecular structure or 4,4″-dihydroxy-3-phenyl-p-terphenyl which has an unsymmetrical molecular structure find problems, for example, that they have only limited solubility in solvents when they are used as raw materials for production of synthetic resins or photoresists. Accordingly, there is a strong demand for novel 4,4″-dihydroxy-p-terphenyls which have improved solubility in solvents so as to be more effectively made use of in a variety of fields as raw materials for production of synthetic resins or photoresists.
According to a known process for the production of 4,4″-dihydroxy-p-terphenyls, 4-methoxy-4′-bromobiphenyl is Grignard-coupled with 4-methoxy-3-phenylmagnesium bromide followed by demethylation, as described in, for example, Japanese Patent Laid-Open No. 2-212449. However, this process uses special raw materials and in addition, it resorts to Grignard reaction so that it costs a great deal and it is difficult to work the process in an industrial manner.
A further process is also known in which 1,1,4,4-tetrakis(4-hydroxyphenyl)cyclohexane is first produced by using 1,4-cyclohexanedione and a phenol, and it is then thermally decomposed and dehydrogenated, as described in Japanese Patent Laid-Open No. 1-168632. However, this process gives 1,1,4,4-tetrakis(4-hydroxyphenyl)cyclohexane or an intermediate raw material only in low yields, and hence the production of the intermediate raw material is costly. The process also needs to carry out the decomposition reaction at a high temperature under a high pressure in an autoclave. Furthermore, the thermal decomposition and dehydrogenation of 1,1,4,4-tetrakis(4-hydroxy-phenyl)cyclohexane fails to provide desired products, that is, 4,4″-dihydroxy-p-terphenyls having a substituent only on one of the terminal 4-hydroxyphenyl groups of the molecule and thus having an unsymmetrical molecular structure.
On the other hand, some of 1,4-bis(4-hydroxyphenyl)-1-cyclohexenes having substituents such as a carboxymethyl group and a naphthyl group (CAS registration number 101789-46-2) or a phenyl group (CAS registration number 202266-25-9) are mentioned in the Chemical Abstracts. However, 1,4-bis-(4-hydroxyphenyl)-1-cyclohexenes having no substituents on either phenolic nuclei or lower alkyl groups only on one of the phenolic nuclei of the molecule are not known.
With regard to 4-(4′-(4″-hydroxyphenyl)cyclohexyl)-1-hydroxybenzenes, 1,4-bis(4-hydroxyphenyl)cyclohexane which is symmetrical with respect to the cyclohexyl group is described in Japanese Patent Laid-Open No. 1-168634 or U.S. Pat. No. 3,408,407. However, 4-(4′-(4″-hydroxyphenyl)cyclohexyl)-1-hydroxybenzenes having lower alkyl groups as substituents only one of the phenolic nuclei are not known, and much less about their trans- and cis-isomers.
Under these circumstances of novel diphenols which have two phenolic nuclei attached to a divalent cyclic hydrocarbon group, the present invention has been completed. Therefore, it is an object of the invention to provide, in particular, novel 4,4″-dihydroxy-p-terphenyls which have lower alkyl groups only on one of the terminal phenolic nuclei of the molecule and hence have an unsymmetrical molecular structure so that they have improved solubility in various organic solvents.
It is a further object of the invention to provide not only novel 1,4-bis(4-hydroxyphenyl)-1-cyclohexenes which have lower alkyl groups only on one of the phenolic nuclei as substituents and are useful as raw materials for production of such 4,4″-dihydroxy-p-terphenyls as mentioned above, but also novel 1,4-bis(4-hydroxyphenyl)-1-cyclohexenes which have no lower alkyl groups on either phenolic nuclei.
It is still an object of the invention to provide 4-(4′-(4″-hydroxyphenyl)cyclohexyl)-1-hydroxybenzenes which have lower alkyl groups on only one of the phenolic nuclei as substituents and which are themselves useful as diols which have hydroxyl group at both the terminals of the molecule for production of, for instance, synthetic resins such as polyesters, polycarbonates or polyurethanes, as well as useful as intermediate raw materials for production of 4,4″-dihydroxy-p-terphenyls.
It is a still further object of the invention to provide trans isomers of the above-mentioned compounds, that is, 4-(trans-4′-(4″-hydroxyphenyl)cyclohexyl)-1-hydroxybenzenes and cis isomers, that is, 4-(cis-4′-(4″-hydroxyphenyl)cyclohexyl)-1-hydroxybenzenes.
In addition, it is also an object of the invention to provide a process for production of a variety of 4,4″-dihydroxy-p-terphenyls in high yield and in high purity under industrially feasible reaction conditions by using raw materials that are industrially readily available.